dry-weather runoff occurs when people waste water through washing their cars in the street, hosing down sidewalks and parking lots, their irrigation systems overspray. narrator: in a city of 12 million people, those seemingly small bits of wasted water accumulate to enormous amounts. shapiro: so all that ends up in our streets, ends up in catch basins, storm drains, into our storm drain system, and for some of the city, parts of the city, it ends up here at smurrf. 350,000 gallons come here on a daily basis, producing recycled water, and that can be reused for landscape irrigation and indoor toilet flushing. the pumps can only handle so much water, which is generally when it's not rain, the dry-weather runoff, so if you get a storm of a decent size, the pumps will shut down automatically and the water will just continue to flow out into the ocean and it carries a lot of bacteria and people can get sick when they're swimming in the water near a flowing storm drain.